What is urea for vehicles?What is the role of truck urea liquid

Since most of the vehicles that drive in our country are gasoline vehicles, and diesel vehicles are mostly large trucks and trucks, many people know very little about diesel vehicles, let alone car urea.And most of us only learned "Oh...there are diesel cars that need to add car urea when selling car urea." So what is car urea? What is the role of car urea? Let's take everyone to find out.

What is urea for vehicles?

Urea for vehicles refers to the selective catalytic reduction (SCR) system of diesel vehicle exhaust, which is used to catalytically reduce nitrogen oxides (NOx) in exhaust gas to harmless nitrogen (N₂) And water (H₂O) liquid.Urea for vehicles is composed of 32.5% high-purity urea and 67.5% deionized water.

About nitrogen oxides in diesel vehicle exhaust

The NOx in diesel vehicle exhaust is mainly nitric oxide (NO) Mainly,If the concentration of NO is too high, it will affect the body's chest and lung functions, causing central nervous system disorders and other hazards. At the same time, it will slowly be converted into nitrogen dioxide (NO₂), NO₂It has a strong pungent odor. Inhalation can cause diseases of the human respiratory system. At the same time, it is also one of the main causes of acid rain, which is extremely harmful to people and the environment.

What is the role of car urea?

From the above, we know that vehicle urea is the liquid used in diesel vehicle SCR system to reduce exhaust NOx pollution.SoHow does car urea reduce NOx pollution?

Unlike gasoline engines,The exhaust pollution of diesel engines is mainly NOx and carbon particles.We generally filter carbon particles through particle traps installed in the exhaust system.(The filtering effect can reach more than 90%).

Regarding the pollution of NOx, it can be dealt with in two ways, namely exhaust gas recirculation system (EGR) and selective catalytic reduction system (SCR).Let's not talk about the EGR system here, but just talk about the SCR system.

Regarding the working process of the SCR system:

SCR is a closed loop injection system,When the exhaust gas is discharged from the engine combustion chamber, the electric pump willYuanAccording to the instruction, suck a sufficient amount of urea solution from the urea tank, mix and atomize the urea solution with compressed air, and enter the spray pipe to spray the urea nozzle evenly into the exhaust gas.at this timeThe urea solution quickly decomposes ammonia gas (NH₃) at high temperature, and at the same time it undergoes a catalytic reduction reaction with NOx, and finally produces harmless N₂And H₂O is discharged.

(In 2008, the National Fourth Standards implemented in my country stipulated that automotive urea must be used in the emission reduction system of diesel vehicles)